World 1 is the first world of the game, and it is without a doubt the smallest one, with the least amount of levels contained within it. There are 8 levels in total here, one of which is down an optional path and one that can be skipped by taking a secret exit. There are also two red Toad Houses, two Green Toad Houses and one Mega Toad House. The red Toad Houses can be reached by going down alternate paths and exits, but green and Mega Toad Houses can only be accessed by spending Star Coins.
- This one's out in the open. You can easily run right into it if you're Mega Mario, or reach it by jumping from the nearby warp pipe the platforms to the left of it.
- Go down the warp pipe right before them midway checkpoint to enter an underground chamber. Get the coin with a simple wall jump. You can't enter the underground area while Mega though.
- This one is plainly visible beneath some brick blocks. As long as you're not normal or Mini Mario, you can ground pound into the blocks to get it.
- The first coin is easily noticeable. Use the bump on the ground a bit to the left to jump on to the roof, then jump to the alcove with the coin.
- In a small brick fortress. Ground pound the top of the structure or use the nearby Koopa's shell to break through.
- Below the alternate exit pipe. See the alternate exit section below to find out how to get to it
- High above the sky. Bounce from a pink mushroom up a trail of coins to grab it.
- This one is on a red mushroom moderately high above the ground. Use the nearby mushroom to get it or float from it from the spin jump around the first Star Coin.
- Between two moving red mushrooms. You can get it even when both mushrooms are facing away.
- The first coin is near a set of moving blocks. You can get it without too much difficulty, but watch out for the Dry Bones nearby.
- At the first cannon pipe, take the harder right path to get to the second Star Coin.
- After launching yourself from the first cannon pipe, fall slightly to the right to reach a door. Go through it to reach a room with the Star Coin.
- In a bonus room accessible through a tiny Warp Pipe, which requires you to be Mini Mario. Wall jump to collect it.
- In an underground area through a warp pipe partially sealed by a brick block. Hit a question mark block to make a P-Switch appear, then activate it and run across the newly-created platforms to reach it.
- In a small pocket of space. Run quickly across the gap as Small Mario to get it.
- Above some bouncy mushrooms. Use the mushrooms to bounce up high and collect it.
- On a narrow red mushroom platform. You need to raise the right scale platform high enough to reach it.
- Near the end of the coin heaven segment accessible from going into the sole warp pipe. You need to be on the moving platform to grab it.
- Out in the open a bit after the section with large bubbles.
- Easily obtained in an above water sub-area, reached via warp pipe.
- Between two horizontal walls near the end. Can be hard to get if you're not small Mario.
- Between two spike ceilings. Wall jump up to grab it.
- Suspended above the lava. Wait for a small stone platform to emerge from the lava before collecting it.
- In a secret area reached via warp pipe. Jump up in the middle of the last tightrope to climb into the pipe.
Just like the warp zones in Super Mario Bros., you can bypass the normal exit pipe if you manage to jump on to the ceiling of the level. To accomplish this, you must tilt the second lever platform as far left as possible, then quickly run to the right and jump. You should reach the small space just above the ceiling. Just run right until you get to a slightly larger space with the third Star Coin and an exit pipe. Go through the pipe and jump to the red flagpole on the other side.
This secret exit opens up a nice shortcut that lets you skip the third level, and even has a red Toad House as a bonus!
For this exit, you will need the uncommon Blue Shell item, which can't be found in levels. You must get it from one of the flying blocks visible from the overworld, or from a red Toad House. Make your way to the room with the third Star Coin. Among the many shifting stone blocks in this room's border, there is a mysterious Mario-sized space that remains open at the upper-right corner. Jump to that spot and go right to enter a secret area. From where you end up, jump around to make some hidden blocks appear, one that contains a 1-Up. If you aren't Shell Mario, you won't be able to progress any further and must go through the yellow pipe to return to the main stage. If you are, dash until you duck into your shell, letting you break through the blocks beneath the yellow pipe. Keep going to break past the wall of blocks covering the red pipe. Enter it to get yourself deposited outside the tower, where the red flagpole is.
This secret exit opens up a path to the World 1 Cannon, which launches you far into the chilly plains of World 5. You might not want to take that big of a shortcut if you're inexperienced, as the spike in difficulty is quite significant.